IP-FAX terminals having an IP-FAX communication function are generally used. An IP-FAX terminal sends data to another IP-FAX terminal through a session initiation protocol (SIP) server when using the IP-FAX communication function. Therefore, the IP-FAX terminal needs to be registered in an SIP server.
In a large-scale network environment, there are cases of preparing a plurality of SIP servers (for example, a primary SIP server and two secondary SIP servers). The secondary SIP server serves as a preliminary device for the primary SIP server, because, even if the primary SIP server cannot operate, IP-FAX communication can be continuously performed thorough the secondary SIP server. In this case, a user may set information on the primary SIP server and the two secondary SIP servers in the IP-FAX terminal in advance. When information on the primary SIP server is correct, registration of the IP-FAX terminal with the primary SIP server is possible. When information on the secondary SIP server is correct, registration of the IP-FAX terminal with the secondary SIP server is possible.
However, the user cannot check whether settings of information on the two SIP servers are correct when settings of the information on the two SIP servers are completed, because, even if the two SIP severs are prepared, the IP-FAX terminal cannot be simultaneously registered in the two SIP servers. When the IP-FAX terminal is successfully registered in the primary SIP server, registration with the secondary SIP server is not performed. Therefore, the user cannot check whether settings of the information on the secondary SIP server are correct or not. The user may check whether settings of the information on the two SIP servers are correct by testing data transmission and reception using each of the two SIP servers. However, the workload of an operator is large.